Regarding stock guns I was wondering has anyone ever competed with a 5.1 and 4.3 as well. I am assuming the 5.1 is more accurate though the 4.3 looks to be a mean contender since it has the middle frame to possible take off any extra little nudge of recoil.

I'm not sure what you mean by that... both the 5.1 and the 4.3 are built on the exact same principles, they are both based off the 2011 build, and both have a mid-frame. I don't see how a mid-frame takes off recoil... could you explain your thought process on that one? I'm curious.

Advantages and disadvantages of both:

Accuracy
5.1 may have a slight edge due to the longer barrel length

Power
Again, the 5.1 may have a slight edge in velocity due to the longer barrel length

Speed
The 4.3 may actually take an edge for cycling speed due to the marginally lighter slide.

I'm not sure what you mean by that... both the 5.1 and the 4.3 are built on the exact same principles, they are both based off the 2011 build, and both have a mid-frame. I don't see how a mid-frame takes off recoil...

Advantages and disadvantages of both:

Accuracy
5.1 may have a slight edge due to the longer barrel length

Power
Again, the 5.1 may have a slight edge in velocity due to the longer barrel length

Speed
The 4.3 may actually take an edge for cycling speed due to the marginally lighter slide.

I use both 4.3 as well as 5.1, although you may not recognize them as such.

It's not a large difference, in fact, I doubt any shooter would notice much of a difference at all. I wouldn't make that your deciding factor on which platform you choose - essentially, they are still the same and can be interchanged easily.

To add to the Accuracy:

The 5.1 may have an additional advantage, as the front and rear sights are further apart, to give a slightly increased degree of accuracy. Plus, the Bomar rear sights of the 5.1 are adjustable, whereas the 4.3 is fixed.

Again, it's not an issue... down the line, you could always switch it up... or if you want, I can get you custom machined 4.3 length slides with rear dovetail sight cuts made to fit the 5.1's Bomar adjustable sight or if you wanted to get real nuts, 10" long slide/barrel/compensator setups... but you also have to realize that will affect maneuverability. lol.

Again, it's not an issue... down the line, you could always switch it up... or if you want, I can get you custom machined 4.3 length slides with rear dovetail sight cuts made to fit the 5.1's Bomar adjustable sight or if you wanted to get real nuts, 10" long slide/barrel/compensator setups... but you also have to realize that will affect maneuverability. lol.

Yes 10" was crazy I learned from my Leon Custom Deagle, it was fun to shoot and a powerhouse but aiming wise it was way too hard as the front of the gun actually jitters up and down unless I used a tactical hand grip which I can't cause I would have to tape it on :P

Custom Illusion Slides? Looks like its time to create a Illusion savings fund.